Institute of Fluid Machinery

CFD-Code - Research - Fluid Structure Interaction (FSI)

Many engineering problems exhibit a behavior whereby the interaction between a flow and the bounding structure cannot be neglected. Some examples are vibrations in hydraulic and ventilation systems, instabilities in aircraft structures, biomedical flows and vibrations in large wind turbines. A prominent example of such interaction is the case of the Tacoma Narrow Bride, whose catastrophic collapse led to the investigation of the flutter phenomenon in civil structures. All these examples can be classified under the name of Fluid-Structure Interaction (FSI).

 

At the Institute of Fluid Machinery it is of great interest to develop methods to analyze the fluid induced vibrations in turbomachinery. At the present time a number of commercial tools offer capabilities for Fluid-Structure Interaction. While these commercial programs are a reasonable choice for the industry (where robust, closed packages are required) they present a number of drawbacks for the academic research. For this reason a complete FSI simulation tool has been developed using the Dynamic Process Management capabilities of MPI. The tool (see Figures 1 and 2) consists of three parts: the in-house-developed coupling program FSiM (Fluid Structure Interaction Simulation Manager), the flow solver SPARC and the open source structural solver CalculiX (http://www.calculix.de/).

 

Tool Diagram

Fig. 1: Scheme of the fluid-structure Interaction tool

 

 

 

Flow diagram

Fig. 2: Program execution and data exchange

 

A first verification stage has been realized with two 2D test cases. The first is the panel flutter problem (see Fig. 3), as an example of an aeroelastic instability. Comparison against reference data shows a good match (see Fig. 4).

 

Flutter Geometry

Fig. 3: The panel flutter problem. After a slight perturbation the flow above the plate (Ma = 0.95) triggers the instability for small h/c

 

Flutter Results

Fig. 4: panel deformation at three stations as compared with reference computations by Massjung et al.

 

 

The second test case is a pulsating channel flow with a flexible obstacle, as an example of resonance.

 

An extension is being performed to account for rotating parts.